1. Field of the Invention
The present invention relates to a mobile internet system, and more particularly, to a mobile internet system and method of controlling operation thereof. Although the present invention is suitable for a wide scope of applications, it is particularly suitable to ensure an efficient operation of a mobile communication terminal during a period of time where scanning and ranging procedures are overlapped with each other in the mobile internet system including the mobile communication terminal performing the scanning and ranging procedures.
2. Discussion of the Related Art
Generally, a mobile terminal enables massive data to be exchanged with a base station at high speed via mobile Internet. There are communication specifications using the mobile Internet such as World Interoperability for Microwave Access (hereinafter abbreviated as WiMAX), Wireless Broadband (hereinafter abbreviated as WiBro) and the like.
The WiMAX is the technical specification developed by many providers in the WiMAX Forum to be taken as the standard for mobile Internet. The WiMAX compensates for the conventional wireless LAN technology by extending the Internet-available range outside buildings considerably.
The WiBro is the wireless mobile Internet solution developed by Ministry of Information and Communication of Republic of Korea, Telecommunication Technology Association (TTA) and mobile communication providers. The WiBro provides a service for mobile ultra-high-speed Internet.
So, the service via mobile Internet enables static or mobile wireless Internet access at high speed using such a mobile Internet terminal as a handset, a laptop, a personal mobile information terminal, a PDA (personal digital assistant), a smart phone, etc.
A mobile communication terminal implementing the mobile internet service transmits a ranging request message to a base station periodically or in case of initialization to decide a network delay or to make a request for the change of power and downlink burst profile.
The mobile communication terminal then executes the ranging procedure in case of receiving a response message to the ranging request message from the base station. In this case, the ranging procedure is periodically executed.
If the signal strength of a base station (hereinafter referred to as a ‘serving base station’) that is exchanging data via mobile internet is irregular or weak, the mobile communication terminal transmits a scanning request message to the serving base station. When a scanning response message corresponding to the scanning request message is received from the serving base station, the mobile communication terminal performs the scanning procedure for a scan duration allocated via the response message. In this case, at least one or more scan durations are set up.
According to the related art, if the mobile communication terminal is authorized to perform the scanning procedure when it is performing the ranging procedure, the mobile communication terminal keeps performing the ongoing ranging procedure instead of switching to and performing the scanning operation for the allocated scan duration.
If the mobile communication terminal is authorized to perform the ranging procedure when it is performing the scanning procedure, the mobile communication terminal stops the ongoing scanning procedure and then preferentially executes the ranging procedure.
In other words, in case that there occurs a duration where the ranging and scanning procedures are overlapped with each other (i.e., both the ranging and scanning procedures are to be performed at a given time), the mobile communication terminal preferentially and always executes the ranging procedure over the scanning procedure. Then the mobile communication terminal is able to execute the scanning procedure after the ranging procedure has been performed and completed. In this case, however, the mobile communication terminal may have a problem that a scan duration has to be re-allocated.
Moreover, if the scanning procedure is interrupted, the mobile communication terminal is unable to make a handover into a neighbor base station having a good channel status at a proper time.